It’s Cascadia Cup time as Sounders FC meets the Portland Timbers at CenturyLink Field in a rivalry 38-years in the making.

Here is a look at three on-the-field matchups to watch for in the derby match.

Osvaldo Alonso vs. Diego Valeri

When the paradox of the irresistible force and the immovable object was first imagined, it was for moments like this. One of the best attacking midfielders in MLS meets one of the best defensive midfielders in MLS as Valeri and Alonso square off. With five goals and 11 assists in 22 matches, Valeri is among the top candidates for MLS Newcomer of the Year. Alonso, meanwhile was an MLS Best XI choice in 2012 and hasn’t missed a beat this year. Portland runs their attack through Valeri and last time around in March, he took a game-high five shots in a 1-1 draw.

Clint Dempsey vs. Will Johnson and Ben Zemanski

It is unclear who Portland Head Coach Caleb Porter will turn to in the defensive midfield role in his 4-2-3-1 formation with Diego Chara out with a one-match suspension for yellow card accumulation and other players out with injuries. However, it is believed that Johnson may be fit to start after missing the previous match with a shoulder injury and Zemanski started in that role on Wednesday night in a 3-3 draw with Real Salt Lake. Whoever plays that role will have their hands full with Dempsey – particularly if he is playing behind Seattle's dangerous forward tandem, further occupying the defense in the middle of the field. Dempsey has yet to figure into the scoring in two matches for Seattle and is hungry to open his account in his MLS return.

Rodney Wallace vs. DeAndre Yedlin

Wallace provides the type of aerial threat that challenges Yedlin while the Seattle right back has the speed to give Wallace issues on the ball. Wallace already has a career high with five goals and five assists, but Yedlin has improved since making his second MLS start when the Timbers and Sounders FC met the first time around. It was Wallace who scored the lone goal for Portland in the meeting last March and this time around Yedin will surely be watching him closely.